1. Field of the Invention
The present invention relates to an exposure apparatus and, more particularly, to an exposure apparatus which has a plurality of illumination optical systems and projection optical systems, and is used for manufacturing a semiconductor element or a liquid crystal display substrate.
2. Related Background Art
Conventionally, liquid crystal display substrates are widely used as display elements for personal computers or TV sets. A liquid crystal display substrate is manufactured by patterning a transparent thin-film electrode on a glass substrate into a desired shape by photolithography. A projection exposure apparatus for exposing an original image pattern formed on a mask onto a photoresist layer on the glass substrate through a projection optical system is used as an apparatus for lithography.
Recently, an increase in size of a liquid crystal display substrate is required. Accordingly, an increase in exposure area is also required for a projection exposure apparatus. As a means for increasing the exposure area, a scanning exposure apparatus having a plurality of projection lenses is available. More specifically, in this scanning exposure apparatus, a light beam emitted from a light source is unified in its light amount through an optical system including a fly-eye lens, and formed into a desired shape through a field stop thereby illuminating the pattern surface of a mask.
A plurality of illumination systems with the above arrangement are arranged, and different small areas (illumination areas) on the mask are respectively illuminated with light beams emerging from the plurality of illumination systems. The light beams transmitted through the mask form the pattern image of the mask on different projection areas on the glass substrate through a plurality of projection lenses, respectively. By synchronously scanning the mask and the glass substrate with respect to the projection lenses, the entire surface of the pattern area on the mask is transferred onto the glass substrate.